In a prior U.S. application of "Concentric Cup Multifoil Insulation", Ser. No. 513,969, filed Oct. 11, 1974, there was described a multifoil insulation package useful in an implantable nuclear powered artificial heart. The insulation consisted of a configuration of very thin nested cups which provided reduced heat loss associated with mitered corner construction at the closed end of the insulation.
The insulation package isolates a temperature controlled region from an ambient region with connection therebetween limited to some means, such as electrical wires, or tubes. Whatever the connection, a penetration through the insulation must be provided. In the prior art, the assembly of cylindrical cups is open at one end, with the penetration region extending through the opening. The open end of the assembly of cups is closed by a stack of foil washers of varying outside diameter alternating with washers of screening. The screening reduces the number of components necessary to install along the relatively long length of the penetration region and also saves weight. The stack of washers and screening forms a fluffed foil. Every so many washers are in contact and are maintained in position by the pressure from the foil cups, thereby forming a mitered joint. Difficulty in preventing heat loss from these mitered joints and in constructing the stack degrades the efficiency of the insulation.
It is therefore an object of this invention to provide an improved multifoil thermal insulation.
Another object to this invention is to eliminate the mitered joint at the penetration region end of a multifoil cylindrical thermal insulation system.